When more detailed attributes about a section are required, then you can request spans. The travel portion of a section is split into spans. The splits occur where any value of the requested attributes change.
More formally, a span is the portion of a section for which a set of attributes is the same. The set of attributes is specified in the request. Each span has an offset that indicates the index in the polyline where the span begins. The end of the span is either the offset of the next span, or to the end of the polyline if there are no other spans.
Span data can be very compact, for example only requesting speed limits on a long highway route can result in a single span for the section. Spans can also be more verbose, for example requesting many attributes within an urban area.
Requesting more span attributes generally results in more spans as this introduces more attributes that can change, and thus requires a new span. Span attributes such as
length do not introduce new spans, but indicate cumulative properties. In this case, the length of the span is in meters.
For sample requests to obtain spans, see these tutorials: